fix(rebuild): make manual /rebuild perform an on-the-spot rebuild with writer-freshness + waiting UI

AGENTS.md

@@ -98,6 +98,29 @@ const table = sqliteTable("session", {
 })
 ```
 
+### Reading a nullable column
+
+Two independent absences meet in one expression, and only one of them is
+`undefined`. `.get()` yields `undefined` when no row matches — Drizzle normalises
+the driver's `null` there — while a nullable column's SQL `NULL` arrives as
+`null`. So `row?.some_column` is `T | null | undefined`.
+
+When a caller only asks "is there a value", flatten to `undefined`, and write the
+flattening as an annotation rather than an `as` cast:
+
+```ts
+// Good — the compiler enforces it; deleting the `?? undefined` is a type error
+const boundary: MessageID | undefined = row?.last_checkpoint_message_id ?? undefined
+
+// Bad — the cast removes `null` from the union without converting anything,
+// so the declared type is untrue at runtime
+return row?.last_checkpoint_message_id as MessageID | undefined
+```
+
+Discriminate a possibly-absent value with truthiness or `== null`, never with
+`=== undefined` / `!== undefined`. Because `null !== undefined` is `true`, such a
+guard typechecks, reads correctly in review, and does nothing.
+
 ## Testing
 
 - Avoid mocks as much as possible

packages/opencode/src/cli/cmd/tui/component/prompt/footer.ts

@@ -0,0 +1,22 @@
+import { Locale } from "@/util"
+
+/**
+ * Cell budget for the ephemeral status message in the prompt footer. Sized so
+ * the message plus the spinner still leaves room for `esc interrupt` and the
+ * context counter on an 80-column terminal.
+ */
+export const STATUS_MESSAGE_MAX = 48
+
+/**
+ * The footer packs the spinner + status message onto the same row as the context
+ * counter (`52.4K/960K (5%)`). A long server-supplied status string wrapped over
+ * several lines and squeezed that row until the counter rendered clipped
+ * (`52.4K/96`). Clamp the message — and flatten any newlines — so a status
+ * string can never cost the counter its cells.
+ */
+export function clampStatusMessage(message: string | undefined) {
+  if (!message) return undefined
+  const flat = message.replace(/\s+/g, " ").trim()
+  if (!flat) return undefined
+  return Locale.truncate(flat, STATUS_MESSAGE_MAX)
+}

packages/opencode/src/cli/cmd/tui/component/prompt/index.tsx

@@ -18,6 +18,7 @@ import { useKeybind } from "@tui/context/keybind"
 import { usePromptHistory, type PromptInfo } from "./history"
 import { assign, expandPlaceholders } from "./part"
 import { usePromptStash } from "./stash"
+import { clampStatusMessage } from "./footer"
 import { DialogStash } from "../dialog-stash"
 import { type AutocompleteRef, Autocomplete } from "./autocomplete"
 import { useCommandDialog } from "../dialog-command"
@@ -1897,11 +1898,13 @@ export function Prompt(props: PromptProps) {
                 {(() => {
                   const busyMessage = createMemo(() => {
                     const s = status()
-                    return s.type === "busy" ? s.message : undefined
+                    return s.type === "busy" ? clampStatusMessage(s.message) : undefined
                   })
                   return (
                     <Show when={busyMessage()}>
-                      <text fg={theme.textMuted}>{busyMessage()}</text>
+                      <text fg={theme.textMuted} wrapMode="none" flexShrink={1}>
+                        {busyMessage()}
+                      </text>
                     </Show>
                   )
                 })()}
@@ -1992,7 +1995,10 @@ export function Prompt(props: PromptProps) {
                   <box gap={2} flexDirection="row">
                     <Show when={usage()}>
                       {(item) => (
-                        <text fg={theme.textMuted} wrapMode="none">
+                        // flexShrink=0: the context counter is the one number the
+                        // footer must never clip (`52.4K/96` instead of
+                        // `52.4K/960K`); the hints beside it can give way first.
+                        <text fg={theme.textMuted} wrapMode="none" flexShrink={0}>
                           {[item().context, item().cost].filter(Boolean).join(" · ")}
                         </text>
                       )}

packages/opencode/src/cli/cmd/tui/context/sync.tsx

@@ -155,6 +155,21 @@ export function bucketMessages<M extends { agentID?: string | null }>(
   return out
 }
 
+/**
+ * A `session.status` event is authoritative for the WHOLE status object.
+ *
+ * Solid's store setter merges plain objects into the existing node
+ * (`mergeStoreNode` only writes `Object.keys(next)`), so writing a bare
+ * `{ type: "busy" }` — which is what the runner emits at the start of every turn
+ * (session/run-state.ts:74) — inherits the `message` of whatever status was
+ * written before it. That latched `/rebuild` outcome text
+ * (session/prompt.ts:4173) into the following turn's spinner. `reconcile()`
+ * drops the fields the new status omits, so each status stands alone.
+ */
+export function nextSessionStatus(status: SessionStatus) {
+  return reconcile(status)
+}
+
 export const { use: useSync, provider: SyncProvider } = createSimpleContext({
   name: "Sync",
   init: () => {
@@ -452,7 +467,7 @@ export const { use: useSync, provider: SyncProvider } = createSimpleContext({
         }
 
         case "session.status": {
-          setStore("session_status", event.properties.sessionID, event.properties.status)
+          setStore("session_status", event.properties.sessionID, nextSessionStatus(event.properties.status))
           break
         }
 

packages/opencode/src/cli/cmd/tui/i18n/en.ts

@@ -560,6 +560,10 @@ export const dict: Record<string, string> = {
   // Session badges
   "tui.session.badge.auto": "Auto",
 
+  // Context rebuild boundary marker (inserted by /rebuild)
+  "tui.session.rebuild_boundary.label": "context rebuilt",
+  "tui.session.rebuild_boundary.detail": "earlier messages summarized",
+
   // Workspace trust
   "trust.title": "Accessing workspace:",
   "trust.safety_check": "Quick safety check: Is this a project you created or one you trust? (Like your own code, a well-known open source project, or work from your team). If not, take a moment to review what's in this folder first.",

packages/opencode/src/cli/cmd/tui/i18n/zh.ts

@@ -581,6 +581,10 @@ export const dict = {
   // Session badges
   "tui.session.badge.auto": "自动",
 
+  // Context rebuild boundary marker (inserted by /rebuild)
+  "tui.session.rebuild_boundary.label": "上下文已重建",
+  "tui.session.rebuild_boundary.detail": "较早消息已摘要",
+
   // Workspace trust
   "trust.title": "访问工作区：",
   "trust.safety_check": "安全确认：这是你自己创建或信任的项目吗？（如你自己的代码、知名开源项目或团队内部项目）。如果不是，请先检查此目录下的内容。",

packages/opencode/src/cli/cmd/tui/i18n/zht.ts

@@ -550,6 +550,10 @@ export const dict = {
   // Session badges
   "tui.session.badge.auto": "自動",
 
+  // Context rebuild boundary marker (inserted by /rebuild)
+  "tui.session.rebuild_boundary.label": "上下文已重建",
+  "tui.session.rebuild_boundary.detail": "較早訊息已摘要",
+
   // Workspace trust
   "trust.title": "存取工作區：",
   "trust.safety_check": "安全確認：這是你自己建立或信任的專案嗎？（如你自己的程式碼、知名開源專案或團隊內部專案）。如果不是，請先檢查此目錄下的內容。",

packages/opencode/src/cli/cmd/tui/routes/session/index.tsx

@@ -1536,7 +1536,16 @@ function UserMessage(props: {
       return parsed ? [parsed] : []
     })[0]
   })
+  // A context rebuild (`/rebuild`) inserts a single user message carrying a
+  // `checkpoint` part plus `synthetic: true` text parts (the rendered context
+  // and index). Neither renders — `checkpoint` has no PART_MAPPING entry and
+  // synthetic text is excluded from `text()` above — so the boundary used to be
+  // completely invisible in the transcript, unlike compaction which at least
+  // leaves a visible summary message behind. Surface it as a one-line marker
+  // row so the user can see that a rebuild happened and where.
+  const rebuildBoundary = createMemo(() => props.parts.some((x) => x.type === "checkpoint"))
   const { theme } = useTheme()
+  const t = useLanguage().t
   const [hover, setHover] = createSignal(false)
   const queued = createMemo(() => props.pending && props.message.id > props.pending)
   const color = createMemo(() => local.agent.color(props.message.agent))
@@ -1603,6 +1612,17 @@ function UserMessage(props: {
           )
         }}
       </Show>
+      <Show when={rebuildBoundary()}>
+        <box id={props.message.id} marginTop={props.index === 0 ? 0 : 1} paddingLeft={2} flexDirection="row" gap={1}>
+          <text fg={theme.textMuted}>
+            <span style={{ bg: theme.backgroundElement, fg: theme.primary, bold: true }}>
+              {" "}
+              ⟲ {t("tui.session.rebuild_boundary.label")}{" "}
+            </span>
+            <span style={{ fg: theme.textMuted }}> {t("tui.session.rebuild_boundary.detail")}</span>
+          </text>
+        </box>
+      </Show>
       <Show when={text() && !actorNotification()}>
         <box
           id={props.message.id}

packages/opencode/src/provider/provider.ts

@@ -1386,7 +1386,7 @@ const layer: Layer.Layer<
           const pluginAuth = yield* auth.get(providerID).pipe(Effect.orDie)
 
           provider.models = yield* Effect.promise(async () => {
-            const next = await models(provider as any, { auth: pluginAuth })
+            const next = await models(provider, { auth: pluginAuth })
             return Object.fromEntries(
               Object.entries(next).map(([id, model]) => [
                 id,

packages/opencode/src/session/checkpoint.ts

@@ -1419,7 +1419,36 @@ export const layer: Layer.Layer<
             .get(),
         ),
       )
-      return row?.last_checkpoint_message_id as MessageID | undefined
+      // Two independent absences meet in this one expression, and only one of
+      // them is `undefined`:
+      //
+      //   row is undefined      -> no such session row. Drizzle normalises the
+      //                            driver's null to undefined here (measured:
+      //                            bun:sqlite's .get() returns null, Drizzle
+      //                            returns undefined), so this half is honest.
+      //   column is null        -> the session exists but no writer has set the
+      //                            watermark yet. SQL NULL, faithfully mapped to
+      //                            JS null, because the column is nullable
+      //                            (session.sql.ts: text().$type<MessageID>()
+      //                            with no .notNull()).
+      //
+      // So `row?.last_checkpoint_message_id` is `MessageID | null | undefined`.
+      // Callers only ever ask "is there a boundary to rebuild from", for which
+      // the last two are the same answer, so flattening to `undefined` is right
+      // — it also matches Drizzle's own row-level convention.
+      //
+      // The flattening is written as an ANNOTATION rather than an `as` cast on
+      // purpose. A cast would let the union be narrowed by assertion, which is
+      // how this went wrong before: the previous version claimed
+      // `as MessageID | undefined` while returning `null`, and a caller that
+      // then wrote `boundary !== undefined` got a condition that is always true
+      // — a guard that typechecks, reads correctly, and does nothing. Every
+      // other caller happened to test truthiness (`!boundary` at prompt.ts:413,
+      // `watermarkBefore ?` at :1131, `boundaryID ?` in nudgedSinceBoundary) and
+      // so never noticed. With an annotation, dropping the `?? undefined` is a
+      // compile error instead of a silent lie.
+      const boundary: MessageID | undefined = row?.last_checkpoint_message_id ?? undefined
+      return boundary
     })
 
     const isWriterRunning = Effect.fn("SessionCheckpoint.isWriterRunning")(function* (sessionID: SessionID) {